Currently there are numerous pneumatic devices in order to seal mains or tubings by the expansion of any of its parts upon receiving the pressure of a fluid inside.
In all of these cases, the pressure to expand and seal the desired area is supplied by means of some auxiliary connections or conduits that communicate the inside of the expandable element with a pressurized source controlled by the operator of the device.
Once the sealing device has been placed in the corresponding area, the expandable element is connected with the pressure source that progressively injects into it the expanding fluid until by means of visual reading means (pressure gage), or by the same appearance or expansion achieved, the pressure source is closed and the disconnection of the sealing device is proceeded with.
The problems posed by this operation are obvious:                The inflating is done by the control of an operator who must follow closely the applied pressure and make sure that the inflating of the seal really takes place.        A connecting-disconnecting process that taking into account the location of these seals (meter boxes, ducting channels, etc.) should be carried out and on occasions this poses serious difficulties.        Time is used in the filling process, which should not be done rapidly because the seal may not adapt adequately to the interstice that it should close up.        